The Roll-Around Attachment will fit a 12" or 16" Auto Dolly (Standard or Heavy Duty). Once attached, you have unimpeded access to the wheel well areas (with the tires/wheels removed) and yet can still move your vehicle in any direction. A real boon to auto restoration projects, painting and body work. (Now you don't have to disturb your masked-off doors to move the vehicle!) Also facilitates an orderly shop or garage and makes sweeping & cleaning so much easier too!